1. Technical Field
This invention pertains to a method and device for preventing sheets of snow from sliding off roofs where that snow has accumulated.
2. Background Art
In climates experiencing snow and prolonged cold weather, snow accumulating on roofs can become a safety hazard. After snow has fallen onto a roof, it may remain in place for an indeterminate period of time. Eventually, as the snow melts, large sheets of snow may break off from the accumulated snow. If the roof on which the snow has accumulated is sloped, such sheets may suddenly fall off the roof onto unsuspecting individuals or property. The weight of such snow sheets is frequently so significant as to cause injury to individuals and serious damage to property.
The hazard caused by accumulated snow may be particularly dangerous when that snow is found on a sheet metal roof. These roofs provide a slippery surface which facilitates sliding of sheets of snow.
A variety of devices for preventing snow from falling from particular types of roofs are known in the prior art. West German Patent 2126082, West German Patent 2523087, Austrian Patent 222329, and Switzerland patent 204783 each teach a type of snow blocking device involving an elongated member which is held above the roof. In each of these patents, the elongated member is held in place by two parallel plates which are secured to each other positioned on either side of a roof seam. Such mechanisms can be useful for particular roof designs in which the roof seams may be snugly fit in between two parallel plates. However, such mechanisms are not easily adapted to fit roof seams of a size or configuration different than the one for which each is designed.
U.S. Pat. No. 2,201,320 to Place teaches the use of multiple sheet metal strips with bent ends to hook over roof seams. Such snow guards may be effective, but must be manufactured to fit the exact distance between adjacent roof seams.
Brackets attached to roof seams to support elongated supports used as scaffolds are described in U.S. Pat. No. 1,054,091 to Darnall. Arguably, another purpose to be served by the Darnall mechanism would be to prevent masses of snow from falling from a roof. Each bracket includes a cam lever which engages a roof seam to attach the bracket to the seam.
Three West German patents, 2845104, 2845103, and 3716491, reveal various mechanisms used to trap snow on a roof. These patents rely on a plurality of snow retainers, each independently attached to a roof seam. In some cases, the retainer appears to be attached to the seam by means of a screw which penetrates the seam, thus possibly lessening the structural integrity of the seam and inviting leaks in the roof. Similarly, the snow guard in U.S. Pat. No. 507,776 to Berger et al. has teeth or projections which pierce the roof seam with possible detrimental results.
While each of these mechanisms known in the prior art is useful for its intended purpose, no mechanism is known which may be easily installed to prevent large masses of snow from falling from a metal roof with standing seams. There exists a need for a mechanism which can be simply secured onto metal roofs of a variety of shapes and sizes, which will decrease the hazard created by sliding snow masses.